CAES

CAES (compressed air energy storage) is one solution to the problem of how to store energy from renewable resources to stabilise the grid.  Atmospheric air is compressed (using solar or wind energy) in a storage tank or, even better, in an underground cavern.  This compressed air is used to drive a turbine when power is required. The advantage of the cavern is that it can be filled with water from an aboveground lake as the air is taken out, reducing the possibility of a vacuum or of damage to the walls of the cavern.  The water is then fed back into the lake as the compressed air goes into the cavern. It’s a nice cycle.

There can also be a means of trapping the heat generated by the compression of the air which can then be used in the decompression process to expand the air.  This adds to the efficiency of the operation. The heat is stored in solids such as stone or concrete, or in fluids such as oil or water.  This removes the need for the burning of fossil fuels to heat the air in the turbine to power the generator.

We need a lot more of these to achieve a stable grid.